Audio/video tape-contacting heads, magnetic tapes, and other metallic and plastic surfaces have been cleaned in the past with various types of solutions that remove dust and other foreign particles and substances. Conventional cleaner solutions have also been used to extend the life of the recorder by improving the tonal and/or visual qualities of the information contained in magnetic and other tapes. These prior solutions have not been entirely satisfactory due to one or more of the following problems: low cleaning power, incompatibility with the surfaces to be cleaned, bad odor, toxicity, and high degree of flammability.
For years, isopropyl alcohol was the standard audio/video tape cleaner, offering excellent cleaning, good evaporation, and a mild odor. Its principal disadvantages were its low flash point, making it flammable, and its internal and ocular toxicity. In specific types of cleaning, certain types of residues are not as effectively cleaned with isopropyl alcohol as with other solutions.
An improved product compared to isopropyl alcohol that gained wide success was "Blend 56" which, at one time, led the market in audio/video cleaner solutions. Blend 56 consists of 85% isopropyl alcohol and 15% Freon.RTM.-TF. The introduction of Freon.RTM.-TF into isopropyl alcohol resulted in a mixture having enhanced cleaning capability because of the synergistic relationship between the two ingredients. The resulting blend efficiently and effectively removes organic residue such as light oil, fingerprints, dust, grime, oxides, and other substances. Freon.RTM.-TF has a high flash point, fast evaporation, low toxicity, and excellent solvency. Its principal disadvantages are environmental concerns involving ozone depletion, and its high expense.
Because of the drawbacks associated with Blend 56, especially the environmental concerns mentioned above, alternatives to Blend 56 are now needed. It is notable that E. I. DuPont de Nemours and Company, Inc., the manufacturer of Freon.RTM., has announced the termination of Freon.RTM. production in accordance with International Convention. Freon.RTM. will still be available through 1999, but its price will be rapidly increasing due to increased cost of production and added Federal taxes, and its availability will be decreasing with each passing year. Freon.RTM. is presently banned entirely in Europe.
Other solutions designed to clean and preserve surfaces are disclosed in the following prior U.S. patents:
U.S. Pat. No. 4,544,413 discloses a chemical solution for use in cleaning and preserving vinyl material, such as phonograph records, and metallic surfaces, such as the tape-engaging surfaces of read-write heads of audio and video tape recorders. The solution includes one or more solvents as carriers for a silicon (e.g., dimethysiloxane polymer), an organo functional silane, and other intermediates such as one or more alcohols, ethers, ketones and halogenated hydrocarbons.
U.S. Pat. No. 4,183,819 discloses solutions and methods for cleaning, polishing and lubricating magnetic heads. These solutions include a mixture of micropulverized inorganic oxides, a mixture of lower alkyl silanes, an alkaline earth metal carbonate, a long chain fatty acid having from 16 to 20 carbon atoms, and a solvent mixture of lower alkyl alcohols having from about 1 to 4 carbon atoms.
In spite of the above exemplary prior solutions for cleaning plastic and metallic surfaces, there continues to exist a need for new and improved solutions of this type. Such solutions are difficult to develop because of a number of requirements imposed on such solutions. For example, an acceptable cleaning solution must: have an acceptable flash point (above 100.degree. F.), have an appropriate evaporation rate, have low odor, not be too corrosive for plastics or other surfaces, be nonaqueous, have low toxicity, not leave undesirable residues, and be environmentally acceptable.
The present inventors have investigated a variety of different mixtures of chemicals in an attempt to discover new types of solutions that could be utilized to clean metallic and plastic surfaces, keeping the above factors in mind. The present invention resulted from such investigations.